The present invention concerns compositions based on peroxide derivatives for the alkaline bleaching of textiles whose performances are superior to those of sodium perborate or sodium percarbonate.
The use of persalts as bleaching agents in formulations for household washing has been known for a long time. In particular, sodium percarbonate and sodium perborate, above all the latter, are currently being used in formulas of major brands of washing compounds such as detergent powders. These persalts are advantageous, since they constitute an effective means for storing hydrogen peroxide in the solid state, thus ensuring a better stability, and they also dissolve in the wash water and liberate the hydrogen peroxide which due to this fact is the true oxidizing agent.
In the alkaline medium of the washing bath, the hydrogen peroxide is unstable and partially decomposes into water and oxygen. The hydrogen peroxide is likewise sensitive to the presence of heavy metal ions whose harmful action can be reduced by the addition of sequestering agents.
In spite of the instability of the hydrogen peroxide, formulations based on persalts, well known in the art, can produce an acceptable bleaching action at temperatures at least equal to 60.degree. C. However, such formulations present two major drawbacks: (1) the performance of the proteolytic enzymes which they generally contain is diminished by the presence of the persalts, and (2) the formulations present a disadvantageous sensitivity to the enzymes, such as catalases, coming from the soil contamination of textiles. Catalases, whose action was described for the first time by THENARD in 1818, have been discovered in blood clots. Certain aerobic bacterias contain them. Catalases cause the decomposition of hydrogen peroxide. Certain persons naturally generate catalase and, thus, during the washing of dirty clothes which they have worn, a persalt such as sodium perborate can be decomposed without there being a bleaching effect.
In order to remedy those drawbacks, it has been proposed in U.S. Pat. No. 3,746,646, to replace the hydrogen peroxide on the persalts with organic hydroperoxides; or, more particularly, because of their generally very low solubility in water, by derivatives of these hydroperoxides such as their alkaline salts. Such a substitution has the disadvantage of not being able to produce a notable bleaching effect except at a temperature higher than that obtained with the persalts or only with the help of activation by transition metal salts inevitably aggravating pollution.